Abstract
This paper presents an experimental and numerical investigation on the flexural behavior of unbonded prestressed concrete (PC) T bridge girders. Three unbonded PC T bridge girders with different prestress degrees spanning 3 m were selected to perform four-point bending tests and then determine the flexural performance. Flexural capacity, crack development and failure mode, load-deflection curves, strain in longitudinal rebars, and stress in prestressing strands of unbonded PC T bridge girders are experimentally analyzed. Subsequently, three-dimensional finite element (FE) models are built and validated by experiments to investigate the effect of different design parameters on flexural behavior of bridge girders. Results generated from experiment and numerical studies show that the flexural destruction behavior in unbonded PC T bridge girders experiences elastic, elastic-plastic, and ductility stages, similar to that of PC T bridge girders. The prestress degree and load location have significant influence on the destruction process in unbonded PC T bridge girders. A lower effective prestress degree can reduce the distribution range in cracks and also increase the width of cracks. Stress in prestressing strands under anchor increases rapidly after concrete presents obvious cracks, and the fracture area within prestressing strands increases with the elevation of prestress degree. The aim of this study is to provide a reference for the design and practical application of unbonded PC T bridge girders.
Highlights
Unbonded prestressed concrete (PC) bridge girders belong to post-tensioned concrete girders with prominent characteristic applying prestress mainly dependent on anchors and little friction between prestressing strands and concrete
Test Equipment and Procedure. e four-point bending test was carried out to investigate the flexural behavior of unbonded PC T bridge girders
A three-dimensional finite element (FE) model, taking into account material and geometric nonlinearity, is established using ANSYS to further investigate the flexural behavior of unbonded PC T bridge girders
Summary
Unbonded prestressed concrete (PC) bridge girders belong to post-tensioned concrete girders with prominent characteristic applying prestress mainly dependent on anchors and little friction between prestressing strands and concrete. In the past few decades, some experiment and numerical studies have been performed to investigate flexural behavior in unbounded PC beams. Peng et al [1] proposed calculation methods on flexural capacity of unbonded PC concrete members together with ultimate stress of unbonded prestressing strands. Kim et al [6] evaluated flexural performance of post-tensioned PC beams with 2400 MPa of high-strength strands dependent on eleven test specimens, and results showed that design criteria provided from ACI 318 [7] and AASHTO [8] underestimated increase of stress in high-strength strands. Limited studies have focused on flexural behavior, including flexural capacity, failure mode, loaddeflection, and stress in prestressing strands of unbounded PC T bridge girders with different prestress degrees. Some recommendations for the design and practical application of unbonded PC T bridge girders are provided to engineers and designers
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